Many industrial applications and business enterprises use heating elements and assemblies containing heating elements (e.g., furnaces and ovens) in various manufacturing processes. For example, the semiconductor industry uses these heating elements and assemblies to heat silicon wafers and other substrate materials that are used in the integrated circuit fabrication process. Wafers are thin slices of material (generally a semi-conductor) used to manufacture microelectronic device (e.g., integrated circuits). The heating elements are used to generate the required temperatures in the heating cycles used in the associated manufacturing processes. For example, it is common to utilize temperatures in the range of 300–1400° C. in common industrial applications.
Because of the thermal stresses caused by temperature cycling degradation attributed to changes in temperature from cold to hot and hot to cold, heating elements generally degrade with use and can eventually fail. If the failure occurs unpredictably and at an inopportune time, serious consequences can result. For example, the failure of a heating element can occur while devices such as a batch of semiconductors, are being heated in a furnace. Consequences of the failure of a heating element used in such a process can include the loss of an entire batch of semiconductor product that is in the oven at the time of the heating element failure. A failure can result in lost revenue, delayed shipments to customers, and a general inability to meet promised and expected yield rates for manufactured components.
It would be very useful, therefore, to be able to determine or predict when a material that makes up a heating element is about to fail. One way of addressing this problem is to conduct a preventative maintenance program by monitoring the amount of time that an item subject to such failures (e.g., a heating element) has been used. After the passage of a predetermined period of time, the item can be replaced prior to an expected potential failure. However, it is often difficult to predict a life expectancy or reliability of heating elements. Moreover, there can be a great deal of variability in the amount and quality of use of such heating elements, and differences in the quality of such items can be diverse as well. In addition, other factors, such as intrinsic or elemental contamination of the materials, can also adversely affect the useful life of such a device.
Accordingly, in view of the foregoing, it would be useful to provide a system and method that predicts or anticipates the potential failure of materials, such as heating elements, due to thermal cycling degradation, so that appropriate corrective action can be pursued prior to the failure of such devices. The present invention achieves the foregoing objectives and solves additional problems, by way of monitoring the condition of heating elements and other devices that can contain materials that experience degradation due to thermal cycling, and providing an indication of a possible pending failure. The present invention is advantageous in that it is easily installed, and can be readily retrofitted to existing equipment. Furthermore, the present invention is minimally invasive, such that it does not adversely compromise the reliability of existing equipment.